Discussion
This is, to the best of our knowledge, the first prospective study on pregnancy outcomes in women with Ebstein’s anomaly. Most women with Ebstein’s anomaly tolerated pregnancy well and there were no maternal deaths. However, in 10% an MACE occurred, most frequently heart failure. Signs of heart failure were found to be a risk factor for MACE.
No maternal mortality occurred in our cohort, which is reassuring and important information to use while counselling these women. In the previously published retrospective series on pregnancy outcomes in women with Ebstein’s anomaly, no maternal mortality was described either.9–15 The incidence of heart failure or thromboembolic events that we found is comparable with the rates reported in a study on pregnancy outcomes in women with CHD (7.4% vs 6.6% and 2.5% vs 1.2%), but arrhythmia seems to be more common in women with Ebstein’s anomaly (3.7% vs 1.2%).20 The retrospective study of Connolly et al, which included 111 pregnancies in 44 women with Ebstein’s anomaly, reported no deaths and no serious maternal complications during pregnancy or post partum, including heart failure, life-threatening arrhythmias, endocarditis or thromboembolic events.10 This contrasts to our data where we observed an MACE rate of 9.9%, despite similar prepregnancy characteristics. The difference could be due to how data were collected in the study of Connolly et al (directly from the women without contacting the obstetricians and cardiologists) as well as its retrospective nature.10 Therefore, we should be aware of the possibility of these serious complications. The heterogeneity of Ebstein’s anomaly can make it difficult to classify everyone with this cardiac disease into the same mWHO risk class, and therefore, an individual assessment seems appropriate. Currently, women with Ebstein’s anomaly are categorised in mWHO class II (corresponding with an expected event rate of 5.7%–10.5%),8 and antenatal visits in a secondary centre are recommended. Our study shows that problems are pronounced in those who had previous evidence of heart failure. Therefore, mWHO class II is indeed appropriate for Ebstein’s anomaly, however, special care should be taken for women with signs of heart failure, who should be treated as mWHO III. In those cases, antenatal visits as well as the delivery should take place in a tertiary centre. Women who have mechanical tricuspid prosthetic valves are another special subgroup of whom a high degree of caution is required, mainly because of the problems inherent in anticoagulant control.
Risk factors for MACE
Signs of heart failure were identified as the only risk factor for MACE during pregnancy. One other study determined individual predictors of poor pregnancy outcomes in women with Ebstein’s anomaly.13 In this American study, based on data from the National Inpatient Sample, anomalous atrioventricular excitation was independently associated with MACE. Patients with Ebstein’s anomaly are predisposed to arrhythmias, especially Wolff-Parkinson-White syndrome (WPW).6 21 In our study, two out of three cases of arrhythmia (one with atrial tachycardia in WPW, one with recurrent supraventricular tachycardia) during pregnancy were in women with heart failure during pregnancy, which suggests an association between the two. No atrial fibrillation or atrial flutter was observed.
Influence of pregnancy on cardiac function
Cardiac deterioration due to pregnancy is a main concern in women with CHD. For example, a previous study in women with transposition of the great arteries with Mustard repair described a deterioration in cardiac function and aortic valve-regurgitation in a subset of patients.22 Therefore, reliable data on the impact of pregnancy on cardiac function is important for women with Ebstein’s anomaly. In our study, no differences in right atrial and right ventricular dimensions were found. Additionally, no deterioration in tricuspid regurgitation was observed. One other study investigated prepregnancy and postpregnancy data in 21 women with Ebstein’s anomaly and also found no clear change in tricuspid valve regurgitation.12
Mode of delivery
In almost half of the women a caesarean section was performed. In our previous report, we found that caesarean delivery was associated with a higher risk of maternal death, postpartum heart failure and an adverse fetal outcome.23 It is also associated with complications in a next pregnancy. Cardiac indications for caesarean section are onset of labour while taking oral anticoagulation, severe heart failure, severe pulmonary hypertension or aggressive aortic pathology8 and in women without these indications or an obstetric indication, a vaginal delivery should be advised and attempted. The ESC guidelines and many supporting studies advise vaginal delivery for women with heart disease.8 23 However, a higher-than-expected number of caesarean sections are still being performed for women with heart disease.23 This suggests that the advice for a vaginal delivery is not being followed in real-life practice and the reasons for this need to be investigated.
Perinatal outcomes
The preterm delivery rate was 25%, which is higher than the global average23 and higher than observed in the rest of the ROPAC cohort (15.6%). Maternal CHD is associated with prematurity and low birth weight.24–26 Despite genetic and epigenetic causes that likely play a role in the pathophysiological mechanism of preterm delivery in women with CHD,27 almost half of all the premature births in our registry were medically indicated. Unfortunately, we cannot distinguish between cardiac or obstetric indications for induction based on the ROPAC data, but perhaps caution of the physician for both mother and child could have contributed to the high rate of medically indicated premature deliveries.
We found that CHD occurred in nearly 5% of pregnancies, including one infant with hypertrophic cardiomyopathy who died 2 weeks after birth. The total CHD birth prevalence reached a stable estimate of 0.8% in the last 15 years.28 The risk of inheriting cardiac defects varies between 3% and 50% depending on the type of parental CHD.29 Previous data also showed a higher risk (6%) of CHD in the children of mothers with Ebstein’s anomaly compared with the general population.30 This emphasises the need for prepregnancy counselling and the advice for fetal echocardiography in all women with Ebstein’s anomaly.
Study limitations
The ROPAC registry reflects a variety of countries and the results are therefore highly generalisable. However, the heterogeneity of Ebstein’s anomaly must be taken into account when interpreting the results of our study. Selection bias is not unthinkable, as we cannot guarantee that all consecutive patients from centres were included, although this was clearly stated as goal before and during the study. The study is registry based, meaning that some disease-specific data are limited or not available. Entering echocardiographic data were optional for ROPAC, therefore, serial echocardiographic data prepregnancy and postpregnancy were available only in a selection of women. Also, it is likely that the echocardiographs prepregnancy and postpregnancy of every woman are performed by different sonographers and thereby variation in sonographer performance should be keep in mind. Unfortunately, detailed data on the type of supraventricular arrhythmias (other than atrial fibrillation or atrial flutter) before pregnancy are not available, such as WPW.